JPS595657B2 - Method for extracting tungsten valuables from tungsten-containing materials - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to the extraction of tungsten valuables from tungsten-containing ores or concentrates.

Tungsten is generally found in nature as sierite (5che
It is found in wolframite (elite, scheelite) type ores and wolframite (wolframite) type ores.

These two types of ores are essentially the same in that their chemical compositions are calcium tungstate and iron manganese tungstate, respectively.

Therefore, different methods have generally been used to extract tungsten values from each type of ore.

In the case of sielite ore, the classic prior art method is to treat the ore with hydrochloric acid to produce insoluble tungstic acid.

Tungstic acid is dissolved in an ammonia solution to finally produce ammonium paratungstate (APT).

Wolframite, on the other hand, is typically decomposed by melting the ore with sodium hydroxide/sodium carbonate to extract the tungsten as sodium tungstate.

The cooled molten product is leached with water to extract the soluble sodium tungstate.

Similarly, it can be treated with hydrochloric acid to precipitate tungestic acid, which can be dissolved in ammonia solution to produce APT.

GB 1,089,913 discloses a method for extracting tungsten values from both sielite and wolframite types of ore or concentrate.

This method involves combining powdered sielite and/or wolframite type ores or concentrates with sodium carbonate,
Melting with a melting agent mixture of sodium chloride and sodium nitrate (which mixture also contains, in the case of calcium-containing raw material, at least sufficient siliceous material to form calcium silicate). and leaching the cooled molten material with water, and separating the tungsten-containing alkaline leachate from water-insoluble impurities, rendering the separated leachate acidic and substantially adding to the organic medium any silicon or phosphorous present. Sufficient fluoride or hydrofluoric acid is added to form an insoluble compound, and the material thus treated is extracted with an organic solution consisting of an organic amine capable of forming a water-insoluble organic amine tungsten complex. the tungsten is transferred from the aqueous phase to the organic phase, the phases are separated, the separated organic phase is treated with aqueous ammonia to produce water-soluble ammonium tungstate, and the aqueous phase containing the ammonium tungstate is transferred to the organic phase. consists of separating from

The process includes as an essential step the melting of powdered ores or concentrates of the schelite and/or wolframite type with a mixture of sodium carbonate and IJium chloride.

In fact, the patent specification states that a fluid melt should be produced.

Typical temperatures at which melting occurs are between 698°C and 825°C.

Fax U.S. Pat. No. 3,800,025 discloses that granulated tungsten-containing ore is heated at approximately 600°C in a moist atmosphere with a small amount of a reagent selected from sodium carbonate and sodium phosphate (in the presence of one type and sodium chloride).
to about 900° C. for about 1 to 3 hours, and leaching the resulting baked product with water to dissolve and filter out the soluble tungsten values. A method for extracting tungsten valuables from tungsten ore is disclosed.

This method is limited to application to low grade tungsten ores and requires a moist atmosphere for operation.

Additionally, relatively high torrefaction temperatures and relatively small amounts of sodium reactant are generally used.

According to the present invention, the ore or concentrate is treated with an alkali metal chloride,
In the presence of a reactive composition selected from alkali metal carbonates and mixtures thereof, high-grade tungsten is produced, comprising the steps of torrefaction without melting and extraction of water-soluble tungsten values from the torrefaction product. A method for extracting tungsten valuables from tungsten-containing ore or concentrate is provided.

It is essential for the process of the invention that the torrefaction takes place without general melting, i.e. the mixture of substance and melting agent must not form a fluid melt during torrefaction. .

Not producing a melt provides great flexibility in process design and can result in energy savings.

The torrefaction product is a material that can be easily processed.

The tungsten values in the torrefaction product will be in the form of water-soluble alkali metal tungstates.

This product can then be processed by known methods to recover tungsten values as tungsten metal.

For example, the tungsten values can be leached from the torrefaction mixture with water and the leachate then treated as described in GB 1,089,913.

These processing steps are essentially applications of chemical reactions known in the art.

The alkali metal for both chlorides and carbonates is always sodium.

The tungsten-containing ore or concentrate is of high grade, ie contains at least 20% by weight of tungsten as tungsten oxide (WO3).

Such materials are generally of the schelite or wolframite type and can contain up to 80.5% tungsten as tungsten oxide.

The reactive composition may be an alkali metal chloride, an alkali metal carbonate, or a mixture thereof.

It is a particularly preferred feature of the process of the invention that the reactive composition consists solely of an alkali metal carbonate, such as sodium carbonate.

Surprisingly, it has been discovered that excellent tungsten recovery rates can be achieved using only sodium carbonate at relatively mild temperatures.

The torrefaction temperature will vary according to the nature of the ore or concentrate being processed and the type and amount of reactive composition present.

The important point is to choose a temperature that is high enough to cause the desired reaction in a reasonable amount of time without causing melting of the ore or concentrate. It is a must.

Generally temperatures within the range of 600° to 800°C are used.

Temperatures as low as 500° C. can be used for wolframite ore and still provide good extraction.

If the collection rate is low, the torrefied product can be dried after filtering and mixed with the reactive reagent again before being torrefied again.

This can continue until the desired amount of tungsten has been extracted from the ore.

Particularly for sierite ores, re-roasting of the ore can be used to increase the tungsten extraction rate.

The amount of reactive composition present during torrefaction also varies according to the nature of the ore or concentrate.

“There should be enough sodium present to combine with all of the tungsten to form sodium tungstate.

However, it has been found that when the treated ore is wolframite, a stoichiometric excess of sodium is generally required.

Roasting must be carried out for a sufficient time to convert as much of the tungsten as possible to sodium tungstate.

Roasting times of 120 minutes or less are typical, although there has been no particular benefit to heating for longer than 60 minutes for the ore.

Depending on the composition of the ore and/or the type of heating equipment used, the reactive composition can also contain a suitable oxidizing agent, such as sodium nitrate, if desired.

Such oxidizing agents are particularly useful when processing wolframite ores or concentrates.

If the tungsten-containing ore or concentrate also contains substantial amounts of calcium, it may be desirable in some cases to include finely divided silica in the reactive composition.

Silica reacts with calcium to form tricalcium silicate, which can then be easily separated from sodium tungstate.

The tungsten-containing ore or concentrate and the reactive composition are generally both ground to a fine powder and intimately mixed before torrefaction.

After roasting, the product can be leached with water.

Experiments have shown that under appropriate conditions, one leaching and replenishment wash is generally sufficient.

The fact that it does not melt during torrefaction means that the torrefaction product can be leached as is, without any steps such as grinding.

Moreover, infusion can be carried out while the roasted product is still hot.

After leaching, the leachate is treated in generally known manner to remove impurities such as aluminum, magnesium, phosphorous, silicon, antimony, arsenic and molybdenum.

After the initial purification step, the tear fluid can be treated with fluoride or hydrofluoric acid for further purification.

The appropriately purified solution is then subjected to conventional solvent extraction operations.

Tungsten contained in the organic phase can be extracted with ammonium hydroxide to produce ammonium tungstate.

Tungsten metal powder can be produced from ammonium tungstate by known methods.

Various sielite and wolframite ores and mixtures thereof were processed by the method of the present invention using different reactive compositions, different ratios of ore to reactive composition, and different torrefaction temperatures.

In all of these experiments, the ore and reactive materials were reduced to fine powder or granular form and roasted as a mixture.

After roasting, tungstic acid (IJum) is leached with water,
The residue was separated from the leachate by filtration and washing, and the leachate was treated in the manner generally described above to recover tungsten values.

The experimental results are shown in the table below.

Reference Examples 1 to 4 The ore used was wolframite ore containing 68.1% tungsten oxide, the reactive composition was sodium carbonate, and the roasting temperature was 650°C.

The stoichiometric ratio of tungsten oxide (WO3) content to reactive composition is about 2.2.

These experiments illustrate the importance of having a stoichiometric excess of sodium present and the excellent recovery rates that can be achieved using the sodium carbonate described above.

The powdered torrefaction product could be easily processed and leached directly while still hot.

Reference Examples 5 to 8 The ore used was sielite ore containing 74.8% tungsten oxide, the reactive composition was sodium carbonate, and the roasting temperature was 650 °C for Experiments 5 and 6.
℃, and 800 ℃ for experiments 7 and 8.

It is noted that the tungsten extraction rate is relatively low.

The reason for this was that less than stoichiometric amount of sodium carbonate was required to prevent melting from occurring.

The torrefied product was powdery and could be leached directly while still hot.

After drying, the leaching residue can be roasted again in the presence of sodium carbonate and leached to increase the tungsten extraction rate.

This can be repeated as often as desired to extract as much tungsten as possible.

Reference Example 9 Ore was roasted at various temperatures using various ratios of reactive composition to ore.

The reactive composition in each case contained 1 part sodium carbonate to 0.67 parts sodium chloride.

The results of these experiments are listed in Table 3.

In all the above experiments, the torrefaction product could be directly leached with water while hot.

The powdered roasted product could be easily processed.

Example 1 In this experiment, sielite concentrate containing WO374.8% and wolframite concentrate containing WO368.1% were mixed in a weight ratio of 1:1, and the mixture was mixed with 1 part of sodium carbonate to 4 parts of the mixture. 1 part with sodium carbonate.

Roasting was performed at 650°C for 4 hours.

As described above, 300 grams of shakeite, 3001 wolframite and 1501 sodium carbonate were mixed and roasted.

The theoretical stoichiometry of sodium carbonate was 98 grams.

The tungsten extraction percentage was 58%.

Example 2 Recarbonation of Experiment IQ Residue Mixed with IJum and roasted at 650°C, and two types of tests were conducted using different amounts of sodium carbonate.

The results are shown in Table 4.

At residue to Na2CO3 ratios of 7:3 and 1:3, the overall extraction of tungsten was 90% and 95%.

The particular ratio selected will depend on the particular circumstances at which any process is performed at any given time.

To the inventor's knowledge, the present invention is the first method found suitable for treating mixtures of schelite and wolframite.

The latter serves to reduce the tendency of sierite to form sticky products.

Claims (1)

[Scope of Claims] 1. From an ore or concentrate containing tungsten, the ore or concentrate is not melted (roasted) in the presence of a reactant which is an alkali metal chloride or carbonate or a mixture thereof. In a method of extracting tungsten valuables by roasting and extracting water-soluble tungsten valuables from the roasted product, the tungsten-containing mineral or concentrate is a high-grade or refined mineral that is a mixture of wolframite and sielite. After extracting the water-soluble valuables from the torrefaction product, the torrefaction product is again melted in the presence of the above-mentioned reactants (roaring, and the water-soluble tungsten valuables are further roasted). A method for extracting tungsten values from a product. 2. The method according to claim 1, wherein the torrefied product is leached while hot to extract tungsten values.